a) Field of the Invention
The present invention relates to an integrated wiring system for an automobile and in particular to a backup system for an integrated wiring system for use in automobiles.
b) Description of the Prior Art
It is known to provide an integrated wiring system for data transmission from a central control unit to a plurality of peripheral processing units, the data transmission being executed under the supervision and control of the central control unit. In this respect, the central control unit is adapted to act upon operator control instructions and to provide output signals indicative of the operator control instructions to a plurality of controllable peripheral devices each of which is adapted to perform a control function. However, when any trouble or abnormality occurs in the central control unit, data transmission is stopped throughout the whole system. Therefore, it is required to provide a fail-safe function using a backup system so as to overcome such data transmission failure, especially when the integrated wiring system is applied to automobiles.
So as to try and overcome the possibility of data transmission failure, it is disclosed in Japanese Patent Laid-Open No. 60-107944 (1985), that data transmission is interrupted because of an occurrence of an abnormality in a central control unit and each of a plurality of peripheral processing units is rendered operative to perform a fail-safe function. Thus, for example, a peripheral terminal processing unit which is assigned responsibility for the control of a lamp of an automobile, operates to turn the lamp ON or OFF in dependence upon the condition which is a fail-safe mode. However, in such a fail-safe condition it is not possible for the operator, for example, a driver, to alter the lamp condition. Where the lamp is a turn indicator or the peripheral device is a wiper motor then the fail-safe condition is normally an OFF condition. Because such a condition cannot be overridden by an operator, it will be appreciated that safety of the automobile is endangered.
The object of this present invention is to provide an integrated wiring system, having improved safety.